The fine increment tilt mechanism for a vehicle with a steering wheel tilt adjustment includes a positive lock that holds a plurality of fixed shoe teeth in engagement with a plurality of teeth on a pivoted shoe rack after a tilt adjustment is made.
Steering columns with tilt adjustments have been used on motor vehicles for many years. A variety of adjustment mechanisms have been used on the steering columns. Some of the tilt columns are infinitely adjustable. Other columns have stepped adjustments. Locks on infinitely adjustable columns tend to be relatively complex and expensive. Steering columns with stepped tilt arrangements have a small number of positions. With a small number of tilt positions, the steering wheel is often either a little too high or a little too low.
One steering column with stepped adjustments that is used on a number of vehicles has a total of seven different positions. The positions are obtained by pivotally mounting a shoe, on a tilt housing, with four grooves that receive a pin on a support housing. The shoe with four grooves can receive the pin, with a tilt housing in four different positions. Each of the four positions are some distance apart because the bar or pin and the one tooth that are loaded in a collision must have substantial thickness to withstand the maximum forces that are applied. To obtain three more positions, a second shoe is added with three grooves that are each between two of the four grooves in the first shoe. Either the first shoe or the second shoe receives the pin in any given position. This system requires a second shoe, a second shoe bias spring, and additional space and still has a total of only seven positions.
Air bags for protection of drivers are mounted on the steering column. Energy absorption systems are also employed on some steering columns. For air bags and energy absorption devices to work properly, tilt adjustments should not change during a collision. Increasing the strength in a steering column, to accommodate the employment of air bags and energy absorption devices, has-been accomplished by increasing the weight and size of component parts.
The fine increment tilt mechanism is employed with a vehicle steering column tilt assembly including a first housing and a second housing. A steering shaft bearing bore, that is coaxial with an upper steering shaft axis, is provided in one of the first and second housings. A pivotal connection pivotally connects the first housing to the second housing for pivotal movement about a tilt axis that is transverse to the upper steering shaft axis. A tilt lock shoe is fixed to the second housing. The tilt lock shoe has a plurality of fixed teeth on an arcuate tooth rack. A tilt lock pivoted shoe is pivotally attached to the first housing for pivotal movement about a pivoted shoe axis that is parallel to and spaced from the tilt axis. The tilt lock pivoted shoe has a plurality of pivoted shoe teeth that are engageable with the plurality of fixed teeth carried by the second housing. A shoe release lever is pivotally attached to the first housing for pivotal movement between a shoe locked position and a shoe unlocked position. The shoe release lever has an integral wedge with a first wedge surface that slides on an arm of the first housing and a second wedge surface that engages a cam lobe on the tilt lock pivoted shoe and cams the plurality of pivoted shoe teeth into engagement with the plurality of fixed teeth when in the shoe locked position. The shoe release lever frees the plurality of pivoted shoe teeth to move out of engagement with the plurality of fixed teeth when in the shoe unlocked position.